How to optimize DLMS Compact Profile and Short Name addressing over Wireless M-Bus (EN 13757) for 15-year battery life?

[marcus_vance]

️ Technical Redaction & Safe Harbor Warning:
Battery discharge profiles and utility meter payload definitions are simulated.

Battery-powered ultrasonic water meters (8.0.1.0.0.255) and gas meters (7.0.1.0.0.255) must operate for 10 to 15 years on a single lithium thionyl chloride cell.
When transmitting DLMS / COSEM over Wireless M-Bus (868 MHz / Mode T1/C1 per EN 13757-4), standard AARQ handshakes and long LN OBIS identifiers consume excessive airtime and RF energy.
What are the recommended frame compression and connectionless paradigms in the Blue Book Ed. 17 Chapter 4.4 for low-power RF?

[elena_rostova]

To achieve a 15-year battery lifespan, the standard architecture employs DLMS Compact Profile and Unsolicited Push (Class 40 0.0.25.9.0.255):

1. Connectionless Unsolicited Push (No SNRM / No AARQ):
   Meters operate as unidirectional transmitters (wM-Bus T1 mode), sending Data-Notification (Tag 0x0F) at fixed intervals (e.g. once every 15 minutes) without waiting for RF receiver ACKs.

2. Short Name (SN) Addressing:
   Replacing 6-byte OBIS Logical Names (LN) with 2-byte Short Name offsets reduces addressing overhead by 66%.

3. Compact-Array (Tag 0x13):
   Instead of transmitting standard A-XDR type tags for every data element, a single template definition precedes raw binary sensor bytes, reducing payload size by up to 60%.

Total transmit duration drops from 120ms to under 18ms, reducing energy consumption per transmission to <0.04 mAs.

[sarah_jenkins]

Looking closely at link-layer security, EN 13757-4 specifies CI fields 0x72 or 0x7A (Short Transport Layer):
AES-128-CTR or AES-128-CBC encryption can be applied directly at the wM-Bus layer, mapping the wM-Bus Access Number (ACC) to the DLMS Invocation Counter.
The receiver gateway decrypts the payload and parses the compact A-XDR stream cleanly per Blue Book Chapter 4.4.

[marcus_vance]

Actually, implementing Compact-Array encoding reduced our total transmitted frame size to 28 bytes for water volume 8.0.1.0.0.255:

0F 00 00 00 01 00 13 01 04 06 00 01 4D 20 02 02 0F FE 16 01 09 04 31 32 33 34

This compact frame carries cumulative volume, flow rate, battery status, and device serial in a single RF burst, easily meeting the 15-year battery life target per IEC 62056-53.